Manage AST NODEs out of GC

NODEs in AST are no longer objects managed by GC.  This change will
remove the restriction imposed by the GC.  For example, a NODE can use
more than five words (this is my primary purpose; we want to store the
position data for each NODE, for coverage library), or even a NODE can
have variable length (some kinds of NODEs have unused fields).
To do this, however, we need more work, since Ripper still uses T_NODE
objects managed by the GC.

The life time of NODEs is more obvious than other kinds of objects; they
are created at parsing, and they become disused immediately after
compilation.  This change releases all NODEs by a few `xfree`s after
compilation, so performance will be improved a bit.  In extreme example,
`eval("x=1;" * 10000000)` runs much faster (40 sec. -> 7.8 sec. on my
machine).

The most important part of this change is `ast_t` struct, which has
three contents: (1) NODE buffer (malloc'ed memory), (2) a reference to
the root NODE, and (3) an array that contains objects that must be
marked during parsing (such as literal objects).  Some functions that
had received `NODE*` arguments, must now receive `ast_t*`.

* node.c, node.h: defines `ast_t` struct and related operations.
* gc.c, internal.h: defines `imemo_ast`.
* parse.y: makes `parser_params` struct have a reference to `ast_t`.
  Instead of `rb_node_newnode`, use `rb_ast_newnode` to create a NODE.
* iseq.c, load.c, ruby.c, template/prelude.c.tmpl: modifies some
  functions to handle `ast_t*` instead of `NODE*`.
* test/ruby/test_gc.rb: ad-hoc fix for a failed test.  The test assumes
  GC eden is increased at startup by NODE object creation.  However,
  this change now create no NODE object, so GC eden is not necessarily
  increased.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60485 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 21 insertions, 14 deletions

diff --git a/ruby.c b/ruby.c
index 94464ab2b9..75f2837d23 100644
--- a/ruby.c
+++ b/ruby.c
@@ -177,7 +177,7 @@ cmdline_options_init(ruby_cmdline_options_t *opt)
     return opt;
 }
 
-static NODE *load_file(VALUE parser, VALUE fname, VALUE f, int script,
+static ast_t *load_file(VALUE parser, VALUE fname, VALUE f, int script,
 		       ruby_cmdline_options_t *opt);
 static VALUE open_load_file(VALUE fname_v, int *xflag);
 static void forbid_setid(const char *, const ruby_cmdline_options_t *);
@@ -1461,7 +1461,7 @@ rb_f_chomp(int argc, VALUE *argv)
 static VALUE
 process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
 {
-    NODE *tree = 0;
+    ast_t *ast = 0;
     VALUE parser;
     VALUE script_name;
     const rb_iseq_t *iseq;
@@ -1674,12 +1674,12 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
         ruby_set_script_name(progname);
 	rb_parser_set_options(parser, opt->do_print, opt->do_loop,
 			      opt->do_line, opt->do_split);
-	tree = rb_parser_compile_string(parser, opt->script, opt->e_script, 1);
+	ast = rb_parser_compile_string(parser, opt->script, opt->e_script, 1);
     }
     else {
 	VALUE f;
 	f = open_load_file(script_name, &opt->xflag);
-	tree = load_file(parser, opt->script_name, f, 1, opt);
+	ast = load_file(parser, opt->script_name, f, 1, opt);
     }
     ruby_set_script_name(opt->script_name);
     if (dump & DUMP_BIT(yydebug)) {
@@ -1704,7 +1704,10 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
 	rb_enc_set_default_internal(Qnil);
     rb_stdio_set_default_encoding();
 
-    if (!tree) return Qfalse;
+    if (!ast->root) {
+	rb_ast_dispose(ast);
+	return Qfalse;
+    }
 
     process_sflag(&opt->sflag);
     opt->xflag = 0;
@@ -1723,10 +1726,13 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
     }
 
     if (dump & (DUMP_BIT(parsetree)|DUMP_BIT(parsetree_with_comment))) {
-	rb_io_write(rb_stdout, rb_parser_dump_tree(tree, dump & DUMP_BIT(parsetree_with_comment)));
+	rb_io_write(rb_stdout, rb_parser_dump_tree(ast->root, dump & DUMP_BIT(parsetree_with_comment)));
 	rb_io_flush(rb_stdout);
 	dump &= ~DUMP_BIT(parsetree)&~DUMP_BIT(parsetree_with_comment);
-	if (!dump) return Qtrue;
+	if (!dump) {
+	    rb_ast_dispose(ast);
+	    return Qtrue;
+	}
     }
 
     {
@@ -1740,7 +1746,8 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
 #endif
 	}
 	base_block = toplevel_context(toplevel_binding);
-	iseq = rb_iseq_new_main(tree, opt->script_name, path, vm_block_iseq(base_block));
+	iseq = rb_iseq_new_main(ast->root, opt->script_name, path, vm_block_iseq(base_block));
+	rb_ast_dispose(ast);
     }
 
     if (dump & DUMP_BIT(insns)) {
@@ -1790,7 +1797,7 @@ load_file_internal(VALUE argp_v)
     ruby_cmdline_options_t *opt = argp->opt;
     VALUE f = argp->f;
     int line_start = 1;
-    NODE *tree = 0;
+    ast_t *ast = 0;
     rb_encoding *enc;
     ID set_encoding;
 
@@ -1894,7 +1901,7 @@ load_file_internal(VALUE argp_v)
 	return (VALUE)rb_parser_compile_string_path(parser, orig_fname, f, line_start);
     }
     rb_funcall(f, set_encoding, 2, rb_enc_from_encoding(enc), rb_str_new_cstr("-"));
-    tree = rb_parser_compile_file_path(parser, orig_fname, f, line_start);
+    ast = rb_parser_compile_file_path(parser, orig_fname, f, line_start);
     rb_funcall(f, set_encoding, 1, rb_parser_encoding(parser));
     if (script && rb_parser_end_seen_p(parser)) {
 	/*
@@ -1912,7 +1919,7 @@ load_file_internal(VALUE argp_v)
 	rb_define_global_const("DATA", f);
 	argp->f = Qnil;
     }
-    return (VALUE)tree;
+    return (VALUE)ast;
 }
 
 static VALUE
@@ -2004,7 +2011,7 @@ restore_load_file(VALUE arg)
     return Qnil;
 }
 
-static NODE *
+static ast_t *
 load_file(VALUE parser, VALUE fname, VALUE f, int script, ruby_cmdline_options_t *opt)
 {
     struct load_file_arg arg;
@@ -2013,8 +2020,8 @@ load_file(VALUE parser, VALUE fname, VALUE f, int script, ruby_cmdline_options_t
     arg.script = script;
     arg.opt = opt;
     arg.f = f;
-    return (NODE *)rb_ensure(load_file_internal, (VALUE)&arg,
-			     restore_load_file, (VALUE)&arg);
+    return (ast_t *)rb_ensure(load_file_internal, (VALUE)&arg,
+			      restore_load_file, (VALUE)&arg);
 }
 
 void *